Lubrication systems perform the task of supplying individual lubrication points or a group of lubrication points, such as at least one part of a bearing, joint, gear, and/or any other part(s) of one or more machines with a varying or non-varying amount of exactly metered lubricant to ensure that no lubrication point is over-lubricated or under-lubricated. Over- or under-lubrication can namely negatively influence a machine component's service life and may result in machine breakdown.
In a lubrication system a lubricant is usually fed to one or more lubrication points using a motor-driven feed pump, such as a piston pump, which ensures that lubricant is dispensed in the required amount. A lubrication system is usually monitored and controlled using components such as lubricant level sensors and switches, pressure switches/gauges and transmitters, flow meters, volumetric meters, oil-streak sensors, dirt indicators, differential pressure switches, motion displays, piston detectors, moisture sensors and temperature measuring devices.
U.S. Pat. No. 8,528,782 discloses a grease gun that includes a housing, a motor positioned within the housing, a pump assembly coupled to and driven by the motor, and a chamber supported by the housing in fluid communication with the pump assembly. The chamber is configured to store a liquid. The grease gun also includes an outlet in fluid communication with the chamber and a measurement system operable to measure an amount of liquid being dispensed through the outlet. The measurement system monitors a change in current of the motor over a cycle of the pump assembly, compares the change in current to a predetermined value, and, if the change in current is greater than the predetermined value, increases a pump cycle counter to indicate that liquid was dispensed. If the change is current is less than the predetermined value, it is inferred that there is an air bubble in the pump assembly or that the chamber is empty. A Hall proximity sensor is used for determining when the piston cycle is completed.